A variety of systems and applications use stacks of sheets or plates, which may be made of metal, paper, plastic, and the like. Printing plates (hereinafter singly or collectively referred to as “plates”) are typically stacked in a cassette or similar container which houses the plates and facilitates their protection, transportation, and handling.
A system for handling printing plates will generally use trays having specific dimensions. Trays can usually be set to contain plates of various sizes, but all plates in the same tray are of one size. The plates may be manually removed from the cassette or the shipping container and inserted into the trays for use by the plate imaging system. Plates packed in cassettes are separated by intermediate paper sheets, hereinafter referred to as ‘separation paper.’
U.S. Pat. No. 5,367,360 (Mcllwraith et al.) describes a method for loading plates from a single tray. In this case, the cardboard shipping container is used as a tray and the plates are lifted and loaded vertically by a vacuum system.
Trays containing printing plates are heavy and bulky, and moving such trays up and down requires complicated and expensive mechanisms and is time consuming. There is a widely recognized need for an automatic and efficient handling system for feeding plates directly from the original plate pallet into the imaging device, while maintaining precise alignment of the plate during the plate feeding process.